Make sure your top thread is above the presser foot. Your timing looks okay, but when the foot advances it breaks the thread if the foot is on the top thread. Making sure the top thread was not being captured by the presser foot solved all my problems.

I know this is super old but if anyone is having this problem, I was able to fix mine by making sure the bobbin timing was correct. It would sometimes do fine and sometimes my thread would get caught up in the bobbin compartment and snap. I had to keep adjusting the bobbin so that the hook (the sharp part seen facing the camera at 2:01) on the bobbin case was picking up the thread but the opposite (as seen facing camera at 1:38) side was not rubbing the thread before it finished the loop.

If you rotate the hand crank clockwise and stop the handle exactly at 12 o'clock, the center of the "half moon" of the bobbin carrier should be pointing at 3 o'clock.

I had the same issue....solved it by sanding the bottom of the tube where the cotton comes out....the groove had burs on it....

Your tensioners are too loose it’s feeding too much thread which makes it go on the Underneath  the bobbin carrier and breaks your thread good luck sir

PS.  There's A LOT of places the thread can get caught on - and break.  Watch every inch along the path carefully.  It might just be something stupid, or a burr where you'd never expect it or can hardly see it.

I know it’s counter intuitive you think that you should tighten the tensioners when breaking the thread. but when they’s to much thread going underneath the carrier and it breaks the thread.

If you have problems on the top side of the stitch, adjust the tension on the bobbin thread.  If you have stitch issues on the bottom side of the stitch, adjust the tension on the frame tensioner.  This sounds backwards but it makes sense if you know how the stitches work.

Thanks for your video. I have a new machine and I'm in the same spot you're in. I /we have to just keep adjusting to make it right.

Spring is broke on the bobbin shuttle... The little screw holding down the flat spring, Half of the spring is gone...
2:07 on the vid...

Remove the remaining piece of broken bobbin tension spring the broken edge is cutting the thread. I removed the spring entirely and the machine worked fine except when using very thin thread to remedy this I made a spring from a very thin piece of plastic never had any more issues

This is why I'm not sure if I should buy one of these. I know zip about sewing.

On mine i found that the "Leaper" , slack take up eyeloop must be directly above the needle bar.  If tilted too far the thread will fray and break after 3-4 stitches, even with the correct timing of the cams and bobbin. Adjusting it above stopped my breaking.

Same issue, rotated the needle flat side towards screw which is counter intuitive and it was fixed. No other changes.

Anyone having this same issue here's how I solved it:  First I swapped out the thread that came with it and used an upholstery thread (issue continued), then I moved my needle down in the needle holder thing a few different lengths and I twisted the needle a tiny bit to align the eye straight on with the arm that holds the bobbin.


It took a few tries, experiments and it didn't seem to get any better, only worse.  Then I guess I hit the sweet spot and it just started working like a charm.



My experience was needle height and eye orientation.  It took me about an hour trying different heights and I adjusted the eye orientation once (and got lucky).

Things to know: any machine, singer, Chinese cobbler, it doesn't matter, will break thread if the tension isn't correct. The correct tension is when the top thread is pulled tight into the material. The bottom tension just needs to be tight enough to pull the thread flat on the bottom of the stitch. To adjust the tension, I use a trick of black thread on top and brown on bottom so I can see it the thread is pulling up slightly into the material on the bottom. If the top tension is wrong there will be loops on the bottom, or thread will break. I took my Dremel tool and ground all the parts that might be close to the needle(where it goes thru the top plate, the groove that goes down next to the shuttle) anyplace that might touch or rub the string.I wanted mine to be able to use a #25 industrial needle for the largest thread I'll use. I can sew now with heavy or light string with no problems. But I mainly wanted this machine to do only heavy thread so that's what I tuned it to. If you watch other's videos you will see that the top tension will break the thread if you do not pull slack between the 'spring' guide and the tensionor with your finger. The workings of the machine should do this automatically when using it.  The tips on setting the bobbin to hit the Scarf correctly, use a marker to 'draw' a line on the needle in the center of the Scarf and have your 'tip' of the bobbin holder This link discusses various issues when sewing. https://www.thesprucecrafts.com/guide-to-fix-your-sewing-machine-2978388

this can also be caused by mismatched thread to needle size. I've found that when this happens to me, a larger needle (for me) solves the issue 100% of the time. In your case though, I'd get a new bobbin carrier tension assembly from bantam tack and possibly a new bobbin carrier as well - just to be on the safe side

Get some braided fishing line,  30 lb test, and sand down the corners of the bobbin, problem solved

I wanted to say that I put a lot of attention on the thread and that cured it. Sounds counterintuitive, but it worked.

Neddle  wrong set up. Try to rotate neddle 180 grad and then rotate main neddle shaft holder a little clockwise and a little counter clock wise. It should solve your issue.